Indian and Chinese border troops had an exchange of gunfire last week just days before a meeting of their foreign ministers, Indian officials said on Wednesday, in a further breach of a decades-old restraint at the frontier.

The two sides have had a long standing agreement for troops not to use firearms at the poorly defined Line of Actual Control or the informal border and for 45 years no shot has been fired.

But since late last month, there have been three incidents of warning shots fired in the western Himalayas where troops are locked in a face-off over competing territorial claims, often in close proximity, officials aware of the situation told Reuters.

“In all these cases shots were fired in the air and not at each other thankfully,” said one of the officials.

One of them occurred on the north bank of the bitterly contested Pangong Tso lake in the run-up to a meeting between Indian Foreign Minister Subrahmanyam Jaishankar and Chinese counterpart Wang Yi in Moscow last Thursday.

The shooting which neither side has made public was the most intense, a second official said. The official said he was not in a position to provide more details but the Indian Express newspaper said 100 to 200 rounds were fired.

The two sides are jockeying for advantageous positions on the un-demarcated mountain border in the Ladakh sector which adjoins Tibet. Last Monday, troops had fired in the air on the southern bank of the lake, the two sides said.

Jaishankar and Wang agreed to dial down tensions and since then the situation has calmed, the Indian officials said. But there is no pulling back of troops yet.

Former Indian military commander lieutenant general D. S. Hooda said distrust was so large now it would be difficult to get back to the agreement under which troops carried few firearms at the contested border during their patrols.

“We should no longer be talking about peace and tranquility along the LAC, but conflict prevention,” he said.